Trying to determine the roofing material. My best guess is that this is PVC. At first I thought it may be Modified bitumen but does not feel like it. It feels more like plastic. Any thoughts from the more experience inspectors who routinely inspect flat roofs?

Looks like TPO from here. The vent boot is definitely a PVC/TPO accessory.

The "asphaltic cement" patch was done by someone trying to stop a leak, I imagine. Wrong product for this material however.

I agree. It might also be white EPDM. Shots of the fastener types might help.

In doing commercial inspections you want to see documentation on any roof membrane before you perform the inspection. If you can't get documentation, state that in your report, because its important in reducing your liability. Without documentation your roof inspection might be limited. Don't say anything in your report that you don't know to be true.

If you're just asking out of curiosity, it can be very difficult to identify a particular membrane type from a photo... and sometimes even on the roof. There have been a lot of commercial roofing products come and go over the years. Lots that are still around have had their formulas changed substantially from when they were first introduced. Some of them are not compatible with underlying materials you can't see. That's why you need the documentation.

Also, warranties are much more complicated for commercial roofing. If your client is expecting you to help keep him out of trouble in that respect, there's a lot to know.

I've been working on CCPIA's commercial roofing courses for a while now. There's good money in it, but a lot of liability due to the much greater number of materials involved compared to residential roofs (both overall and in individual roof systems), how much those materials have changed over the years, how differently flat roofing systems perform in different climates, and the complicated warranty issues.

Based on my experience (I've represented Duro-Last Roofing in the past, and sold commercial and residential roofing for over 10 years), I would definitely say that is NOT Duro-Last (a brand of PVC-blend membrane roofing). Based on the poor workmanship (the corner weld would never pass muster with a manufacturer tech inspection), I would say that it is a TPO roofing membrane. I also noted several edges that are caulked. These are cut edges that require a sealant to prevent moisture from wicking into the membrane (single plies are often constructed with a reinforcement sandwiched between layers of thermoplastic membranes). This would indicate a PVC or more likely, a TPO (thermoplastic polyolefin) The earlier comment that the repair at the chimney is not an approved, compatible repair is also true. It would void any warranty for either TPO or PVC products. Neither play well with asphaltic materials. Regardless of the material brand or composition, this roof would need to be inspected by a qualified roofing company (many residential-only companies are not versed on single-ply membranes, so I would recommend a company that does commercial projects).